Robert Dicke

Robert Henry Dicke (1916-1997) was one of the greatest physicists in history. He made significant contributions to radar, atomic physics, cosmology, quantum optics, gravity physics, and astrophysics. Dicke was the most accomplished American-born physicist and yet was denied the Nobel Prize, despite winning numerous merit-based awards.[1]

Like the great British physicist Fred Hoyle, Dicke paid a heavy price for criticizing a theory favored by liberals (in the case of Dicke, he criticized the Theory of Relativity; in the case of Hoyle, he criticized the theory of evolution).

Bob held some 50 patents, from clothes dryers to lasers. He recognized that two mirrors make a more effective laser than the traditional closed cavity of microwave technology. In the company Princeton Applied Research he and his students packaged his advances in phase-sensitive detection in the now-ubiquitous "lock-in amplifier." With its successors this probably has contributed as much to experimental Ph.D. theses as any device of the last generation. Bob predicted and experimentally showed that collisions that restrict the long-range motions of radiating atoms in a gas can suppress Doppler broadening. The physics is the same as that of Mössbauer narrowing of gamma-ray lines; it is used in the atomic clocks of the Global Positioning System. He contributed to the concept of adaptive optics in astronomy. He was among the first to recognize that the accepted gravity theory, general relativity, could and should be subject to more thorough tests. His series of gravity experiments mark the beginning of the present rich network of tests. He set forth the idea of the anthropic principle that now plays a large part in speculation on what our universe was doing before it was expanding. Bob's visualization of an oscillating universe stimulated the discovery of the cosmic microwave background, the most direct evidence that our universe really did expand from a dense state. A key instrument in measurements of this fossil of the Big Bang is the microwave radiometer he invented.

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The Brans-Dicke Theory of Gravitation

While Dicke accepted portions of the Relativity, both special and general, he believed that plain General Relativity did not fully explain gravity. Along with his former student Carl Brans, he formulated the Brans-Dicke theory, which includes a scalar field in addition to the tensor field defined by general relativity. This "scalar-tensor theory" (as opposed to plain relativity, which is just a "tensor theory") included a scalar field, usually denoted ω, which, when assigned a certain value, they believed matched experimental data better. (When ω is set to infinity, the Brans-Dicke theory becomes equivalent to plain General Relativity.) Brans and Dicke suggested a value of about 5. The observable differences between Brans-Dicke and general relativity are extremely tiny, but the Mariner and Cassini spacecraft (below) clearly detected this[3]
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Dicke was instrumental in proposing extremely sensitive tests of General Relativity. Modern measurements of the various tests, specifically from the Mariner 6 spacecraft in 1970 and the Cassini spacecraft in 2004, show that plain Einsteinian relativity, not the Brans-Dicke theory, agrees with observation.[3] Nevertheless, interest in the Brans-Dicke formulation has recently revived, in the context of dark matter / dark energy investigations.

No Nobel Prize

The Brans-Dicke gravitation theory is not widely accepted today, and neither is Fred Hoyle's "steady state creation" theory. But both men made other groundbreaking contributions. Dicke was probably punished by the Nobel committee for advancing the Brans-Dicke theory, and he never got full credit for his invention of the lock-in amplifier, and his insights into the Big Bang theory and the cosmic background radiation.[4]

Biography

Dicke was born on May 6, 1916 in St. Louis, Montana. He received a bachelor's degree from Princeton University in 1939, as well as a doctorate from the University of Rochester in 1941. In the same year he became a staff scientist at the radiation laboratory of MIT. In 1975 he was appointed Albert Einstein professor of science and nine years later he became emeritus professor.[5]

Dicke's work was closely related to that of Arno Penzias and Robert Wilson, who first measured the cosmic background radiation, though Dicke was the theorist who explained it.[6] The 1978 Nobel Prize for Physics was awarded to Penzias and Wilson, but not Dicke, for this work. Some people think that this was unfair, and that Dicke should also have won the Nobel Prize for any of his many other achievements also (such as his laser work).